Sheet metal repair jig

ABSTRACT

A sheet metal repair jig for smoothening a sheet metal by heating and cooling a part of the sheet metal to be repaired includes at least one roller having a cylindrical shape, the roller being made of an electrically-conductive material and serving as a heating means; a roller support shaft supporting the roller pivotably about an axis of rotation of the cylindrical shape; a support supporting the roller support shaft and having an electrode electrically connected to the roller; and a cooling channel serving as an air channel for discharging cooling air to a contact surface between the part of the sheet metal to be repaired and the roller. The cooling channel is formed inside the roller support shaft and has a discharge port that discharges the cooling air to the contact surface between the part of the sheet metal to be repaired and the roller.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Application No.2011-101763, filed Apr 28, 2011, which is hereby incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a sheet metal repair jig for repairingdents or distortions generated in a curved surface or in a peripheralsurface of a sheet metal used for vehicles or the like.

BACKGROUND

In repairing dents or distortions in a sheet metal of, for example, anautomotive body which were caused by contact, crash, etc., first, thelocation of a dent or distortion is identified, accessories of a panelrequiring repairs are detached, and coating applied to the identifiedlocation of the dent or distortion is removed. Next, with a puller orthe like, the sheet metal having the dent or distortion is roughlyflattened out by pulling, hammering, welding, etc. Then, the dent ordistortion is heated and cooled repeatedly so as to utilize expansiondue to heating and contraction due to cooling.

As a sheet metal repair jig for repairing dents or distortions in asheet metal, the following art has been proposed (see JP Utility ModelAppl. Publ. No. 3,154,968). This sheet metal repair jig includes: aroller serving as a heating means; a roller shaft for pivotablysupporting the roller; and a U-shaped holding frame serving as a bearingfor the roller shaft. By using this roller as a heat source and movingthe roller at constant speed and in contact with a part to be repaired,an uneven heat distribution in the sheet metal is suppressed and repairworks can be carried out without producing scratches.

As mentioned above, works for repairing dents or distortions in a sheetmetal require heating and cooling to be repeated. In this respect, inthe aforementioned conventional art, the use of a roller has facilitatedthe heating operation itself. However, to cool a part of a sheet metalto be repaired, the operator had to put a heating roller down and thenpick up a separately-prepared cooling device to perform a coolingoperation. Therefore, the operator needed to use the heating device andthe cooling device alternately in carrying out the repair work, whichwas troublesome to the operator.

Further, high tensile strength steel sheets or the like used for recentautomotive bodies are weak against heat, and thus needs to be expandedby being heated at a low temperature. It is important that the steelplate is cooled immediately after heating in order to avoid an excessivetemperature rise. However, in the conventional sheet metal repair jig,since the operator each time had to alternate between the heating meansand the cooling means, it was difficult to cool the sheet metalimmediately after heating. Further, when there was a time lag fromheating to cooling, the temperature of the heated part may become higherthan the control temperature of the heating means, depending on thedegree of contact between the heated part of the sheet metal and theroller.

The present invention proposes to solve the aforementioned problem ofthe conventional art, and it is an object of the present invention toprovide a sheet metal repair jig that can smoothly heat and cool a partof a sheet metal to be repaired to enhance precision of repair and toreduce the operator's workload.

SUMMARY

In order to solve the aforementioned problem, according an aspect of theinvention, a sheet metal repair jig for smoothening a sheet metal byheating and cooling a part of the sheet metal to be repaired, includes:

at least one roller having a cylindrical shape, the roller being made ofan electrically-conductive material and serving as a heating means;

a roller support shaft supporting the roller pivotably about an axis ofrotation of the cylindrical shape;

a support supporting the roller support shaft and having an electrodeelectrically connected to the roller; and

a cooling channel serving as an air channel for discharging cooling airto a contact surface between the part of the sheet metal to be repairedand the roller,

wherein the cooling channel is formed inside the roller support shaftand has a discharge port that discharges the cooling air to the contactarea between the part of the sheet metal to be repaired and the roller.

According to the above aspect, cooling air is discharged to an area inthe vicinity of the roller of the sheet metal repair jig that is incontact with a part to be repaired. Therefore, it is possible to coolthe sheet metal immediately after heating with the roller. Also, usingthis roller for heating allows not only a drawing process but alsosmoothing of a surface to be repaired with the roller, enabling a moreprecise repair.

Since a sheet metal used for automotive bodies or the like is formedinto a curved surface or the like, a residual internal stress exists. Inthis case, after the heating, if the heated sheet metal is subject tonatural heat radiation or is left to let cool, the shape etc. of thecurved surface of the sheet metal is distorted. Therefore, the sheetmetal needs to be cooled immediately after heating. In this respect, inthe present aspect, the sheet metal can be cooled immediately afterheating, since cooling air is discharged from a discharge port through acooling channel simultaneously with the heating by the roller.

According to this aspect of the invention, particularly, it is possibleto repair heat-sensitive materials, e.g., high tensile strength steelsheets, at a low temperature, since the steel plate can be preventedfrom reaching an unnecessarily high temperature even when heated by theroller.

Conventionally, since the heating means and the cooling means wereseparately provided, after a part of a sheet metal to be repaired hasbeen heated, the operator puts down a heating device used for heatingand then holds a cooling device to carry out cooling. In this respect,according to the present aspect, both heating and cooling can beperformed with a single device, thereby significantly eliminating theburden on the operator.

As a device for discharging gases in the vicinity of the point ofoperation, such devices as those used for CO₂ welding or MAG welding aretypically known. However, the discharge gas of these devices serves as ashielding gas for preventing a metal melted by arc welding from beingexposed to air. Accordingly, this discharge gas totally differs from thecooling air of the present invention in terms of technical idea.

The temperature of the roller may increase above the control temperaturedue to an increase and decrease in the resistance depending on theextent of contact area or due to contact over a long period of time. Inthis respect, in the present aspect, since the sheet metal can be cooledby the cooling means immediately after the roller has contacted thesheet metal, the temperature is less influenced by both the contact areaor the contact time. Thus, in sheet metal repair works in which expertskills are ultimately of importance, it is possible to provide a jigthat eliminates the difference in skill between the inexperiencedoperator and the expert.

Preferably, the sheet metal repair jig includes a plurality of rollersarranged along the axis of rotation, and the discharge port is formed ina gap between the plurality of rollers.

With the sheet metal repair jig of the above configuration, the sheetmetal repair jig includes the plurality of rollers, and the dischargeport for discharging cooling air is formed in a gap therebetween.Therefore, the cooling air can be supplied uniformly in the widthdirection of the contact surface between a part of the sheet metal to berepaired and the roller (in a direction of the roller shaft).

Preferably, the sheet metal repair jig includes two rollers of the samesize and shape, and the discharge port is formed in a gap between thetwo rollers.

With the sheet metal repair jig of the above configuration, the sheetmetal repair jig includes two rollers, and a port for dischargingcooling air is formed in a gap situated centrally between the rollers.By discharging the cooling air from the discharge port toward a contactsurface between the roller and the sheet metal, the cooling air can besupplied uniformly across the entire contact surface between the rollerand a part of the sheet metal to be repaired.

According to the aforementioned present invention, it is possible toprovide a sheet metal repair jig that can smoothly heat and cool a partof a sheet metal to be repaired to enhance precision of repair and toreduce the operator's workload.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an overall constitution of asheet metal repair jig according to an embodiment of the presentinvention.

FIG. 2 is a plan view illustrating an overall constitution of a sheetmetal repair jig according to an embodiment of the present invention.

FIG. 3 is a schematic side view illustrating an operation of a sheetmetal repair jig according to an embodiment of the present invention.

FIG. 4 is a plan view illustrating an overall constitution of a sheetmetal repair jig according to another embodiment of the presentinvention.

FIG. 5 is a perspective view illustrating an overall constitution of asheet metal repair jig according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Hereinafter, the present invention will be described with reference tothe drawings illustrating embodiments thereof

1. Present Embodiment

A sheet metal repair jig 1 according to an embodiment (hereinafter thepresent embodiment) is a jig configured to repair a sheet metal made of,for example, a general steel plate, an aluminum sheet metal, astainless-steel sheet metal or a high tensile strength steel sheet bysmoothening a part of the sheet metal to be repaired by heating andcooling. As shown in FIGS. 1 and 2, the sheet metal repair jig 1includes: a roller 2 having a cylindrical shape and made of anelectrically-conductive material; a roller support shaft 3 supportingthe roller 2 pivotably about an axis of rotation of the cylinder; asupport 4 supporting the roller support shaft 3; an electrode 5 disposedat one end of the support 4 and electrically connected to the roller 2;and a cooling channel 6 serving as a channel for discharging cooling airto a contact surface of the roller 2.

The roller 2 is a heating means which produces resistive heat when anelectric current is passed through. The roller 2 has a cylindrical shapeand is made of an electrically-conductive material such as copper orferrite. In the present embodiment, sheet metal repair jig includes tworollers of the same size and shape, or, the roller 2 includes twoportions (rollers 2 a, 2 b) of the same size and shape. A gap betweenthe two rollers 2 a, 2 b is preferably as small as possible as long asthe function of the discharge port 6 b is achieved, although it dependson a size of a discharge port 6 b to be described later.

Here, the roller 2 is made of copper or ferrite, and not of carbon asdisclosed in JP Utility Model Appl. Publ. No. 3,154,968, which ismentioned above. This is due to the following reasons. In JP UtilityModel Appl. Publ. No. 3,154,968, heat generation performance ismaintained without generating an arc. However, as pointed out in JPUtility Model Appl. Publ. No. 3,154,968, carbon is less wear-resistantthan copper and wears down at a higher rate. Therefore, when used for aroller, there were cases where a part of a sheet metal to be repairedcould not be flattened out appropriately due to worn away unsmoothcarbon. In the present embodiment, this disadvantage of carbon iseliminated by adjusting a current flowing into the roller, as well as byproviding a cooling means described below and using copper or ferritewhich is more wear-resistant.

The roller support shaft 3 is a rod-shaped object which pivotablysupports the two rollers 2 a, 2 b. The roller support shaft 3 has ahollow section extending from one end to an intermediate position, i.e.,an almost central position in the width direction, forming a coolingchannel 6 to be described hereinafter. Further, the discharge port 6 bdescribed below is formed in a gap part between the two rollers 2 a, 2b.

The support 4 is U-shaped in a plan view and is configured to supportthe roller support shaft 3 at both end portions. In the presentembodiment, as shown in FIG. 1, the roller support shaft 3 isinternally-threaded at both end portions and is secured to the support 4with nuts N such that the support 4 is sandwiched therebetween. It is tobe noted that the method of securing the support shaft 3 to the support4 is not limited to this securing manner, but any publicly-known varioussecuring methods may be employed as long as the roller support shaft 3is secured to the support 4.

The electrode 5 is formed at a bottom part of the U-shape of the support4 having a U-shaped configuration in a planar view and is disposed in adirection perpendicular to the roller support shaft 3. The electrode 5serves as a connecting portion to be electrically connected to anexternal current supply unit, which is not shown. As such a currentsupply unit, a publicly-known device such as the one disclosed as asheet metal repair jig body in JP Utility Model Appl. Publ. No.3,154,968 is used.

The roller 2, the roller support shaft 3, the support 4 and theelectrode 5 are each comprised of an electrically-conductive member. Anelectric current which is input into the electrode 5 via the externalcurrent supply unit, which is not shown, flows into the roller 2 throughthe support 4 and the roller support shaft 3.

The cooling channel 6 is a cooling air conveying path that is formed ina hollow in the roller support shaft 3. At one end portion of thecooling channel 6, an air intake port 6 a for introducing air from anexternal blower (publicly-known), which is not shown, is provided. Atthe other end portion thereof, the discharge port 6 b that dischargesthe introduced air is provided. A flow channel 6 c is formed between theair intake port 6 a and the discharge port 6 b.

The air intake port 6 a is formed at one end portion at which thesupport 4 pivotably supports the roller support shaft 3, and when anair-blast nozzle of the blower is connected to the air intake port 6 a,the air intake port 6 a becomes a port for introducing cooling air. Thedischarge port 6 b in a gap between the two rollers 2 is formed at anaxially central portion of the roller support shaft 3.

The discharge port 6 b is formed by a nozzle 6 n. With this nozzle 6 n,a discharge direction of the discharge port 6 b is directed towards adirection of a contact surface in which the roller 2 contacts the sheetmetal, i.e., a direction perpendicular to a direction of a plane in theplan view of FIG. 2. A setting angle of the discharge direction isdetermined based on the reason described below. When using the sheetmetal repair jig 1 in repair work, a connecting portion of a currentsupply unit, which is not shown, is connected to the electrode 5. Theconnecting portion of the current supply unit is exteriorly providedwith a handle made of an insulating material. The operator grips thehandle and moves the repair jig with the U-shaped plane surface of thesupport 4 being substantially aligned with the plane surface of thesheet metal (see FIG. 3). Therefore, with a discharge port beingprovided in a direction of the U-shaped planar surface of the support 4,the discharge port 6 b can supply cooling air in the vicinity of thecontact surfaces between the two rollers 2 a, 2 b and the sheet metal.As described above, the discharge direction of the discharge port 6 bset by the nozzle 6 n is directed toward the contact surface between theroller 2 and the sheet metal. However, the direction of the dischargeport 6 b can be varied appropriately, depending on an angularrelationship between the electrode 5 or the operator handle and asurface of the sheet metal to be repaired. Preferably, the direction ofthe discharge port 6 b is set in a direction in which cooling airdirectly hits a surface of the sheet metal to be repaired.

In the present embodiment, any type of gas, e.g., air and nitrogen, aswell as carbonic acid gas (CO₂), can be used as air to be dischargedfrom the discharge port 6 b, as long as a part of the sheet metal to berepaired can be cooled.

The sheet metal repair jig 1 of the present embodiment constituted inthe foregoing manner operates in the following manner. First, theelectrode 5 of the sheet metal repair jig 1 is connected to an externalcurrent supply unit (publicly-known device is used), which is not shown.In turn, an air-blast nozzle of a blower (publicly-known), which is notshown, is connected to the air intake port 6 a provided at one end ofthe roller support shaft 3 so as to define an air flow path of coolingair.

Next, the operator grips the handle provided at the connecting portionof the external current supply unit connected to the electrode 5 andstarts operation. At this time, the current value of the externalcurrent supply unit is controlled to control the temperature at whichthe sheet metal repair jig 1 contacts the sheet metal.

Then, while gripping the handle, the operator makes the roller 2 contacta part of the sheet metal to be repaired and rolls the roller 2 withrespect to the surface to be repaired. At this time, a predeterminedelectricity flows into the roller 2 from the external current supplyunit via the electrode 5, the support 4 and the roller support shaft 3and a resistive heat is produced in the contact surface between theroller 2 and the sheet metal, and thereby a part of the sheet metal tobe repaired is heated. Simultaneously, cooling air is supplied from theexternal blower. The cooling air passes through the air intake port 6 aand the cooling channel 6 and is discharged from the discharge port 6 b.

Here, as shown in a schematic side view of FIG. 3, when the sheet metalrepair jig 1 is in use, the nozzle provided on the discharge port 6 b ofthe cooling channel 6 is provided so as to be almost opposite a surfaceof the sheet metal to be repaired A. Therefore, cooling air to bedischarged from the nozzle is discharged from a region between the tworollers 2 a, 2 b, hits the surface of the sheet metal to be repaired,spreads to right and left, and further spreads out across the contactsurfaces between the rollers 2 a, 2 b and the sheet metal.

In the sheet metal repair jig 1 of the present embodiment describedabove, since the cooling air is discharged to an area in the vicinity ofthe roller 2 which is in contact with a part to be repaired, the heatedpart can be immediately cooled after the heating with the roller 2.Also, with the heating by such a roller, smoothing of the surface to berepaired with the roller as well as a drawing process is possible and amore precise repair is enabled.

Since a sheet metal used for automotive bodies or the like is formedinto a curved surface or the like, a residual internal stress exists. Inthis case, after the heating, if the heated sheet metal is subjected tonatural heat radiation or is left to let cool, the shape of the curvedsurface etc. of the sheet metal is distorted due to the residual stress.Therefore, the sheet metal needs to be cooled immediately after heating.In this respect, with the sheet metal repair jig 1 of the presentembodiment, the sheet metal can be cooled immediately after heating,since cooling air is discharged from the discharge port 6 b through thecooling channel 6 simultaneously with the heating by the roller 2.Particularly, it is possible to repair heat-sensitive materials, e.g.,high tensile strength steel sheets, at a low temperature since the steelsheet can be prevented from reaching an unnecessarily high temperatureby being heated with the roller 2.

Conventionally, since the heating means and the cooling means wereseparately provided, after a part of a sheet metal to be repaired hasbeen heated, the operator puts down the sheet metal repair jig 1 usedfor the heating and then holds a cooling device to carry out cooling. Inthis respect, with the sheet metal repair jig 1 according to the presentembodiment, both heating and cooling can be performed with a singledevice, thereby significantly eliminating the burden on the operator.

As a device for discharging gases in the vicinity of the point ofoperation, such devices as those used for CO₂ welding or MAG welding aretypically known. However, the discharge gas of these devices serves as ashielding gas for preventing a metal melted by arc welding from beingexposed to air. Accordingly, this discharge gas totally differs from thecooling air of the sheet metal repair jig according to the presentinvention in terms of the technical idea.

The temperature of the roller 2 may increase above the controltemperature due to an increase or decrease in the resistance dependingon the extent of contact area, or due to contact over a long period oftime. In this respect, with the sheet metal repair jig 1 of the presentembodiment, since the sheet metal can be immediately cooled by thecooling means after the roller has contacted the sheet metal, thetemperature is less influenced by the contact area or the contact time.Thus, in sheet metal repair works in which expert skills are ultimatelyof importance, it is possible to provide a jig that eliminates thedifference in skill between the inexperienced operator and the expert.

Also, a plurality of rollers 2 are arranged along the axis of rotation,or, the roller 2 is divided into portions (in this case, into two), andthe discharge port 6 b for discharging cooling air is formed in a gaptherebetween. Therefore, as shown in FIG. 3, the cooling air can besupplied uniformly in the width direction of the contact surface betweena part of the sheet metal to be repaired and the roller (in direction ofthe roller shaft). Particularly, in the present embodiment, two rollersare arranged along the axis of rotation, or, the roller is divided intotwo sections, and a port for discharging cooling air is formed in a gapsituated centrally between the rollers. By discharging the cooling airfrom the discharge port formed opposite the contact surface between theroller and the sheet metal, the cooling air can be supplied uniformlyacross the entire contact surface between the roller and a part of thesheet metal to be repaired.

2. Other Embodiment

The present invention is not limited to the aforementioned embodimentbut may include the embodiment described below. Specifically, althoughin the present embodiment, two rollers 2 are arranged along the axis ofrotation, or, the roller 2 is divided into two sections, and thedischarge port 6 b is formed in the support shaft 3 centrally betweenthe two rollers, the present invention is not limited to thisembodiment, and three or four, or more rollers may be provided, or, theroller may be divided into three or four, or more sections.

For example, like a sheet metal repair jig 10 shown in FIG. 4, threerollers 20 are arranged along the axis of rotation, or, the roller 20 isdivided into three, and two air intake ports 60 a are provided at bothends of the rollers 20 so that the discharge ports 60 b are formed inthe two gaps between the rollers 20. In this embodiment, as shown inFIG. 4, the constitution can be employed as follows. Flow channels 60 care formed by the hollow sections of a roller support shaft 30, the flowchannels 60 c extending from both ends of the roller support shaft 30,respectively, to the first discharge ports 60 b situated in theone-third positions in the width direction so that two cooling channels60 beginning from both ends are formed, and two discharge ports 60 b areformed accordingly. Also, as a variant, although not shown, anotherconstitution may be employed wherein a hollow section is formed toextend from one end of the roller support shaft to the two-thirdsposition in the width direction so that a flow channel is provided, anddischarge ports are provided in the middle and end portions.

In this embodiment, the discharge direction of the nozzle 6 n comprisedof the discharge port 6 b is directed in a direction perpendicular tothe direction of the plane in the plan view of FIG. 2. However, thepresent invention is not limited to this embodiment, but for example,the discharge direction of the nozzle 6 n can be directed in the samedirection as the axis of the electrode 5, i.e., in a directly downwarddirection in a perspective view of FIG. 1 or in a schematic view of FIG.3. Alternatively, the discharge direction of the nozzle 6 b may bedirected in an oblique direction, which is an intermediate directionbetween the direction perpendicular to the direction of the plane of theplan view of FIG. 2 and a direction which is the same as the directionof the axis of the electrode 5. In other words, depending on the angleat which the roller 2 contacts a part of the sheet metal to be repaired,the discharge direction of the nozzle 6 n is preferably directed in thesame direction as the direction in which the roller contacts the sheetmetal. It is also possible to employ another constitution wherein, forexample, the nozzle 6 n is pivotably attached to the support shaft 3 sothat the discharge direction of the discharge port 6 b for cooling airwith the nozzle 6 n is variable.

As a variant of the embodiment shown in FIG. 1, in addition to theembodiment in which cooling air is introduced from the end portion ofthe support shaft 3, an embodiment shown in FIG. 5 is possible. FIG. 5is a schematic plan view of a sheet metal repair jig 20 according to thevariant. In FIG. 5, for the sake of convenience of explanation, thesupport 4 is cut out above the roller 2 and illustrated in crosssection.

As with the sheet metal repair jig 20 shown in FIG. 5, anotherconstitution may be employed wherein a cooling channel 61 is formedperpendicular to the support shaft 3 in a gap between the rollers 2 a, 2b and an air intake port 61 a for cooling air is formed in an endportion of the cooling channel 61. In order to supply air, a hose (shownby a phantom line in the drawing) extending from an external blower,which is not shown, is attached to the air intake port 61 a of thecooling channel 61. Also, in this case, a discharge port 61 b is formedon the straight line of the introduction path of the cooling channel 61.The manner of using the sheet metal repair jig 20 is the same as theembodiment shown in FIG. 3.

Also, in this embodiment, as shown in FIG. 5, it is also conceivable toprovide a constitution in which, in a portion of the support shaft 3covered with the roller 2, the cooling channel 61 situated centrallybetween the rollers 2 a, 2 b diverges horizontally inside the supportshaft 3 and penetrate into end portion positions of the support shaft 3,and the ventilation holes 61 d which communicate the cooling channel 61inside the support shaft 3 with the rollers 2 a, 2 b and, are providedat central portions of the rollers 2 a, 2 b.

In this way, by providing the ventilation holes 61 d in a portion of thesupport shaft 3 covered with the rollers 2 a, 2 b, a flow of airdischarged from the ventilation holes 61 d is produced within smallclearances between the support shaft 3 and the backside of the rollers 2a, 2 b, as indicated by the arrows in FIG. 5. This enables the rollers 2a, 2 b to be cooled by the cooling air. Thus, it is possible to carryout repair treatment while the rollers 2 a, 2 b are kept at a lowtemperature to some extent.

The ventilation hole 61 d may be of a circular or rectangular shape.Also, the ventilation hole 61 d may be a single hole or a plurality ofholes provided in each roller. Further, in FIG. 5, from a design pointof view, the cooling channel 61 penetrates through the support shaft 3,and both ends are closed with the nuts N with caps. However, there areno functional problems as long as both end portions of the coolingchannel 61 extend from the central portion in which the air intake port61 a and the discharge port 61 b are formed to the positions of bothventilation holes 61 d.

1. A sheet metal repair jig for smoothening a sheet metal by heating andcooling a part of the sheet metal to be repaired, comprising: at leastone roller having a cylindrical shape, the roller being made of anelectrically-conductive material and serving as a heating means; aroller support shaft supporting the roller pivotably about an axis ofrotation of the cylindrical shape; a support supporting the rollersupport shaft and having an electrode electrically connected to theroller; and a cooling channel serving as an air channel for dischargingcooling air to a contact surface between the part of the sheet metal tobe repaired and the roller, wherein the cooling channel is formed insidethe roller support shaft and has a discharge port that discharges thecooling air to the contact surface between the part of the sheet metalto be repaired and the roller.
 2. The sheet metal repair jig accordingto claim 1, wherein the sheet metal repair jig includes a plurality ofrollers arranged along the axis of rotation, and the discharge port isformed in a gap between the plurality of rollers.
 3. The sheet metalrepair jig according to claim 2, wherein the sheet metal repair jigincludes two rollers of the same size and shape arranged along the axisof rotation, and the discharge port is formed in a gap between the tworollers.